Continuous monitoring of structural deformation is an important task in engineering geodesy, particularly for historic buildings affected by long-term uneven settlement and changes in structural behaviour. This study evaluates the applicability of a biaxial tiltmeter for continuous monitoring of changes in the tilt of the bell tower of St. Paul's Lutheran Cathedral in Odesa and for identifying when additional geodetic observations are required. The sensor was installed on the northern wall of the bell tower at a height of 30 m. Angular observations along two orthogonal axes were processed as daily means and converted into conditional linear displacements. From 26 September 2025 to 28 February 2026, the trajectory was predominantly oscillatory, without sustained displacement accumulation. From the beginning of March to 27 April 2026, a directional trend developed, reaching approximately -2 mm along the X axis and +30 mm along the Y axis. Terrestrial laser scanning indicated a bell-tower tilt change of approximately 21 mm between 26 December 2024 and 27 April 2026, with a prevailing positive Y component. The results are qualitatively consistent but not numerically equivalent because the methods characterize different geometric quantities and height intervals. The tiltmeter can detect changes in the deformation regime and support event-based scheduling of additional surveys, but it cannot replace precise levelling, total-station measurements, or terrestrial laser scanning.
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